Which of the following are ionic carbides?

$A$ red coloured mixed oxide $(X)$ on treatment with conc. $HNO_3$ gives a compound $(Y).$ $(Y)$ with $HCl$ produces a chloride compound $(Z)$ which can also be produced by treating $(X)$ with conc. $HCl.$ Compounds $(X),$ $(Y),$ and $(Z)$ will be

The correct statements among the following are:
$(A)$ $BeH_2$ and $MgH_2$ are polymeric in nature.
$(B)$ $LiH$ is unreactive to oxygen at moderate temperatures.
$(C)$ $BeH_2$ and $MgH_2$ possess significant covalent character.
$(D)$ The stability of alkali metal hydrides follows the order $LiH < NaH < KH < RbH < CsH$.

'Bordeaux mixture' is used as a fungicide. It is a mixture of

Which of the following pairs of atomic numbers represents elements belonging to the $s$-block?

Which of the following mixtures is known as fusion mixture?